Coin processing machines receive coins and sort, count, or verify the coins. A conventional coin processing machine may include a guide surface that defines a coin path that extends besides and along the guide surface. The guide surface may be straight or may be arcuate depending on the design of the machine.
A singulated, serial stream of coins roll or slide against the guide surface while moving along the coin path. Because the positions of the coins moving against the coin guide surface are accurately known, coin sensors are often placed in the guide path to sense the presence and denomination of the coins.
FIG. 6 illustrates in part a known coin processing machine 10 of this type. The coin processing machine 10 has proven in practice to be a reliable and durable device that accurately sorts, counts, or verifies coins at high speed.
Coin processing machine 10 has a stationary flat plate 12 that receives a stream of singulated coins (represented by the arrow 14) from a turntable (not shown). A stationary guide finger 16 is mounted on the plate 12. The guide finger 16 has an elongate, straight guide surface 18 that defines a coin path 20 extending on the plate 12 besides and along the guide surface 18. A coin drive (not shown) drives the stream of coins against the upstream end of the guide surface 18. The edges of the coins remain against the guide surface 18 as the coins slide on the plate 12 and move downstream along the coin path 20.
A set of coin sensors 22 is carried in the plate 12, the sensors 22 being serially spaced along the coin path 20 in order to sense a portion of a coin spaced from the guide surface 18 moving over the sensor. The sensors 22 are arranged downstream in order of decreasing coin diameter. Each sensor 22 is associated with a coin diameter/coin denomination that is the smallest diameter coin that would be sensed by the sensor 22 as the coin moves on the coin path 20 while against the guide surface 18. Because the sensors 22 are arranged in order of decreasing coin diameter, the illustrated coin sensors 22 are each respectively associated as one moves in the downstream direction with the current US half-dollar coin, US dollar coin, US quarter-dollar coin, US five-cent coin, US one-cent coin, and US ten-cent coin respectively.
Each coin sensor 22 generates a respective signal 23 representing the presence of a coin when a coin passes over the sensor. The signals are transmitted to a controller 24. The controller 24 generates an output signal representing the denomination of a coin passing the set of coin sensors 22 based on which coin sensor 22 first signals the presence of the coin. Operation of the controller 24 and sensors 22 is described in my U.S. Pat. No. 7,243,774 (which patent is incorporated by reference as if fully set forth herein) for a set of sensors serially spaced along a guide surface and so will not be described in great detail here.
The sensors 22 are arranged to first detect the largest diameter coin (in the illustrated embodiment a US half-dollar coin) and then detect each succeeding smaller-diameter coin as a coin in contact with the guide surface 18 passes sequentially past the sensors 22. The controller 24 determines which sensor 22 first generates a signal to determine the denomination of coin moving past the array of sensors and maintains a running count of the value and number of the coins processed by the coin processing machine 10.
In operation, it has been found that occasionally a coin received onto the plate 12, particularly a wet or oily coin of relatively small diameter, does not move against the guide surface 18 but remains spaced away from the guide surface 18 as the coin passes the sensors 22. See FIG. 7, which illustrates a coin D (a US ten-cent coin) that is not against the guide surface 18 but is instead moving along a misaligned coin path represented by the arrow 26. The coin D first passes over the most upstream sensor 22 as shown in the figure, which sensor generates a signal 28 that is incorrectly interpreted by the controller 24 as representing the presence of a half-dollar coin. The ten-cent coin D is valued in error as a half-dollar coin.
Thus there is a need to avoid errors in assigning values to coins that are not properly located against the guide surface as the coins move through the coin processing machine.